A transfer mold is typically used in the semiconductor industry to encapsulate a semiconductor device due to its high molding accuracy and low cycle time for conducting the encapsulation process. During the encapsulation process, a semiconductor device is clamped by the transfer mold while a molding material (e.g. epoxy resin) is injected through a runner. The molding material then flows from the runner through an opening (technically known as a ‘gate’) of the transfer mold to reach a molding cavity in which the semiconductor device is located. Encapsulation of the semiconductor device into a molded package subsequently takes place.
To adapt the transfer mold for use in semiconductor device encapsulation, an inside gate wall of the transfer mold has to be electroplated to prevent the molding material from adhering thereto. Otherwise, it will be difficult to remove the molding material from the inside gate wall of the transfer mold and a build-up of remnant molding material may result in blockage of the gate opening leading to the molding cavity, thereby affecting the encapsulation process.
Generally, it is not possible to coat the inside gate wall of the transfer mold by utilizing a conventional apparatus for the electroplating process. Due to the conical configuration and depth of the inside gate wall, the electric field generated by an electrical current will be stronger at the outer surface of the transfer mold and weaker at the inside gate wall.
Thus, it is an object of the present invention to seek to provide an apparatus that can be used to coat the inside gate wall of the transfer mold using general electroplating principles.